ProSoft Technology MVI46-MCM User Manual

Page 83

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MVI46-MCM ♦ SLC Platform

Reference

Modbus Communication Module

User Manual

ProSoft Technology, Inc.

Page 83 of 108

March 29, 2011

5.6

Modbus Protocol Specification

The following pages give additional reference information regarding the Modbus
protocol commands supported by the MVI46-MCM.

5.6.1 Commands Supported by the Module

The format of each command in the list depends on the MODBUS Function Code
being executed.

The following table lists the functions supported by the module.

Function
Code

Definition

Supported in
Master

Supported in
Slave

1

Read Coil Status

X

X

2

Read Input Status

X

X

3 Read

Holding

Registers

X X

4

Read Input Registers

X

X

5

Set Single Coil

X

X

6

Single Register Write

X

X

8 Diagnostics

X

15

Multiple Coil Write

X

X

16

Multiple Register Write

X

X

17

Report Slave ID

X

22

Mask Write 4X

X

23 Read/Write

X

Each command list record has the same general format. The first part of the
record contains the information relating to the communication module and the
second part contains information required to interface to the MODBUS slave
device.

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